Is it okay to defend my mother and “Khala” from my uncles’ words?

In a recent incidence my real uncles (chacha) said unpleasant words for my mother and my whole maternal relatives. This was communicated to my father by me (21years), my elder brother (25 years), and eldest brother (29 years) but he did not say anything to them instead father took side of his brothers. These types of things are quite usual since my mother’s marriage in this family since 30 long years. As we (children) have grown up, it hurts us a lot to see my mother in the same state of being targeted for every petty issues they come across. They are even jealous of my brother’s progress. My “khala” is married to one of my uncles and even she is targeted the way my mother is. I do not directly call my uncle’s because I know I will also utter bad words which will jeopardize my “Akhlaq” and I don’t want to do it. Is it permissible for me to defend my mother and scare them (my uncles) to not to say even a single word for my mother and “Khala”, If they will do it, they will be punished? Please guide me.